The Analysis On The Effect Of The Loading Capacity Of The Pile With Buried Tubes

With the development of economy and the increasing concern over the environmental problems, more and more attention is being paid to the Ground-source heat pump (GSHP) system, which is environment-friendly and energy-saving. Many scholars have done further research in the Ground-source heat pump system, which has been used in many domestic and foreign constructions. At present, the vast initial investment becomes a major obstacle to the development of the Ground-source heat pump system. The traditional ground heat exchanger takes the form of vertical U-tube in bore holes. However, the high cost of drilling bore holes, which accounts for a large percentage of the initial investment, leads to a vast initial investment. Taking into account the cost, accuracy and technical complexity of the traditional ground heat exchanger, people begin to use the "pile ground heat exchanger". In current studies, the U-tube heat exchangers are buried in the foundation of buildings, but their small transfer area may cause a "thermal short circuit", so the pile heat exchangers with spiral coils are proposed, which have no such drawbacks. Ground heat exchangers inside foundation piles can also bear a certain amount of air conditioning load and the remaining part can be borne by ground heat exchangers in vertical-bore holes. In this way, the initial investment can be reduced greatly and the area of heat exchangers can also be reduced.It is a new technology to bury tubes in the pile,on which few studies, applications and engineering practices have been done. Currently the major problems are as follows:further research needs to be done on the loading capacity features of the pile with buried tubes and many problems of it are to be solved; a comprehensive and systematic research is rarely seen both home and abroad. It can't show the effects of the tubes on the loading capacity features to copy or slightly modify the research of the pile without buried tubes. Besides, the effects of the buried tubes on the loading capacity features of the pile have restricted the development of ground heat exchanger technology. As a result, the study of the effects of buried tubes on the loading capacity features of the pile will be beneficial for further development of the technology of buried tubes.In order to study the effect of the loading capacity of the pile with buried tubes,firstly, based on the comparison tests on piles with buried tubes and piles without buried tubes, a study has been done on the load-carrying and deformation states of the pile over compression, bending and tension respectively, and the effects of buried tubes on the loading capacity features have been analyzed. The FEM software ANSYS has been employed to make numerical simulations of the compressed piles, the bending piles and the tensiled piles. The theoretical analysis corresponds to the test results. Secondly, combined with specific examples of pile engineering, through comparison between the results of static loading test and the results of ANSYS analysis, the effects of buried tubes on the loading capacity features of the pile have been decided on through ANSYS analysis, which has been conducted by selecting appropriate calculating parameter; Afterwards, a lot of numerical analysis has been done to decide on the effects of changes in the length of the pile, the diameter of the pile, the diameter of spiral coil and the distance of spiral coil on the loading capacity features of the pile.